This is Cool!

When someone receives a head injury in most sports, a cold pack is immediately applied to reduce brain swelling. Brain swelling is bad because your skull doesn't give the brain much room to expand, subjecting it to undue pressure which can lead to death. So it makes sense that creating a system capable of immediately cooling your brain upon impact could reduce the chances of injury or death should you land on your head. That's the thinking behind ThermaHelm, the company has created a retrofittable chemical cold pack designed to activate upon impact and capable of fitting into existing helmets.

I'm still waiting for the foam stuff from Demolition Man (the old Sylvester Stallone movie) remember it? he went through the sign in the car and the foam filled the car and hardened to keep him safe....